No. 104 - Miljøstyrelsen

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52 effects and even if the value is applicable for a few hours’ exposure and thus covers a longer period of exposure than for cleaning after breakage of a fluorescent lamp, the value of 1 mg Hg/m 3 is used as the LOAEL value, since it is the lowest reliable value identified for short-term exposure. The value is derived from occupational exposures in the working environment and the time of exposure is close to identical to the cleaning scenario, so the value of 1 mg Hg/m 3 is used directly as the LOAEL value. The LOAEL value is based on observations of humans, i.e. there is no (un)certainty factor (= 1) for interspecies differences. As standard is used a factor 10 as (un)certainty factor for intraspecies differences. For differences in duration of exposure no (un)certainty factor (= 1) is used since the LOAEL value is based on acute effects. For issues relating to dose-response the REACH Guidance Documents state an (un)certainty factor of 3-10 to convert from LOAEL to NOAEL, but it is stated that an (un)certainty factor of 3 should be used in most cases. For the quality of the whole database a further (un)certainty factor may be used. Altogether, an (un)certainty factor of 1 x 10 x 1 x 3 x 1 = 30 is used. This (un)certainty factor of 30 results in: DNEL short value = 0.033 mg Hg/m 3 (33 µg Hg/m 3 ). This value, after calculation with the (un)certainty factors, is close to the Danish occupational threshold limit value, which is set at 0.025 mg Hg/m 3 (25 µg Hg/m 3 ). Long-term exposure (DNEL ) long Most data on health effects of long-term exposure to mercury vapours is derived from occupational exposure. Many existing limit values for mercury vapours are based on a LOAEL value of 0.025 mg Hg/m 3 (25 µg Hg/m 3 – identical to the Danish occupational threshold limit value). A recent study (Richardson et al., 2009) recommends LOAEL at 0.014 mg Hg/m 3 (14 µg Hg/m 3 ) for long-term exposure to mercury vapours. A NOAEL value for long-term exposure of 0.010 mg Hg/m 3 (10 µg Hg/m 3 ) is used to determine the DNEL value since a LOAEL requires an additional certainty factor of at least 3. The NOAEL value is converted to long-term exposure (as described in section 4.7) by multiplying with 5/7, as well as a factor 10/20 to take into account all seven days of the week and the total respiration volume of 24 hours. This gives 0.004 mg/m 3 as the corrected NOAEL value for an exposure of 24 hours a day over a long period of time. The NOAEL value is based on observations of humans, i.e. there is no (un)certainty factor (= 1) for interspecies differences. As standard is used a factor 10 as (un)certainty factor for intraspecies differences. For differences in duration of exposure no (un)certainty factor (= 1) is used since the NOAEL value is already based on chronic effects. For issues relating to dose-response it is stated that an (un)certainty factor of 3-10 can be used to convert from LOAEL to NOAEL. Here, it is not necessary to convert values, since it is a NOAEL value, so no (un)certainty factor is needed. For the quality of the whole database a further (un)certainty factor may be used. Altogether, an (un)certainty factor of 1 x 10 x 1 x 1 x 1 = 10 is used. This (un)certainty factor of 10 results in:
DNEL long value = 0.0004 mg Hg/m 3 (0.4 µg Hg/m 3 ). This value is close to the USEPA long-term reference concentration without harmful effects (RfC) of 0.0003 mg Hg/m 3 as stated in Table 4-2. 5.2.3 Risk assessment scenario 1: Short-term exposure for 30 minutes The short-term exposure is calculated above in section 5.1.4 ‘Exposure calculations with and without ventilation’ (see Table 5-2). It is seen that the calculated concentrations in the breathing zone, regardless of quantities of mercury in the fluorescent lamp, exceed the DNEL short value of 0.033 mg Hg/m 3 (33 µg Hg/m 3 ), when it is assumed that there is no ventilation in the room and assuming a momentary evaporation of 10 % of the total amount of mercury at the time t=0. This is an exceedance of around 2 to 60 times. With a content of 5 mg Hg in the lamp the exceedance is 8 times the DNEL short value and 10 times the Danish occupational threshold limit value. However, this calculation is as mentioned a worst-case calculation and a fictive calculation, since there will always be some natural ventilation. In Table 5-2 are also stated calculated concentrations in the breathing zone, when ventilation is taken into account. The values marked by green background are below the DNEL short value of 0.033 mg Hg/m 3 (33 µg Hg/m 3 ). Calculations show that after 10 minutes’ ventilation with all doors and windows open the mercury concentration in the breathing zone of 2 m 3 will be below the DNEL short value for compact fluorescent lamps with a low content of mercury (≤ 2.5 mg Hg) and thereby not constitute an acute risk. After 15 minutes’ strong ventilation the concentrations in the breathing zone will be below the DNEL short value for compact fluorescent lamps with the presently permitted content of mercury (≤ 5 mg Hg), and after 30 minutes the mercury concentration is below the DNEL short value for all calculated levels of mercury in compact fluorescent lamps and straight fluorescent lamps. Thus, calculations show that with the assumption that 10 % of mercury has evaporated during the first 30 minutes the concentration of mercury in private homes will be above the DNEL short value and thus constitute a risk – unless strong ventilation is ensured. Ventilation has a very significant impact in view of lowering concentrations of mercury down to non-hazardous levels in the home during an accident. However, it should be noted that the DNEL short value has been calculated based on a LOAEL value for an exposure of a few hours (not specified in more detail). In a cleaning scenario the cleaning time will probably only be about 10 minutes – in the worst case 30 minutes as assumed in the calculations. In case of fast clean-up the exposure time may be shorter than the one for which the DNEL short value has been calculated and this means that the exposure to mercury in this shorter period of time is in reality much lower and thereby does not constitute a health hazard. Generally, however, many factors have an impact on the assessment of the real risk: 53
Page 1 and 2: Survey and health assessment of mer
Page 3 and 4: Contents PREFACE 5 SUMMARY AND CONC
Page 5: Preface This ”Survey and health a
Page 8 and 9: 8 Forms of mercury in compact and s
Page 10 and 11: 10 � Ordinary ventilation: Is slo
Page 13 and 14: 1 Introduction 1.1 Purpose and cont
Page 15: Table 1-1 Maximum permitted content
Page 18 and 19: 18 � Light bulbs without integral
Page 20 and 21: 20 Figure 2-3. Example of lamp with
Page 22 and 23: 22 2.3 Survey of types of mercury c
Page 25 and 26: 3 Release of mercury from broken la
Page 27 and 28: momentarily at the time t=0, i.e. t
Page 29 and 30: same in both 30 cm’s and 1.5 mete
Page 31 and 32: Table 3-1 Values for contents of Hg
Page 33: pieces of broken glas and adhesive
Page 36 and 37: 36 Physico-chemical data Physical s
Page 38 and 39: 38 Table 4-1 Estimated daily averag
Page 40 and 41: 40 No information is available abou
Page 42 and 43: 42 Table 4-2 Limit values etc. for
Page 44 and 45: 44 A LOAEL of 0.025 mg Hg/m 3 (25
Page 46 and 47: 46 5.1.2 Calculation method For the
Page 48 and 49: 48 In practice, thus, a maximum of
Page 50 and 51: 50 To allow for the impact from ven
Page 54 and 55: 54 � These calculations assume mo
Page 56 and 57: 56 as the source of exposure (the b
Page 58 and 59: 58 Evaporation of mercury will take
Page 60 and 61: 60 Den Store Danske, 2009. In Danis
Page 62 and 63: 62 NEMA, 2000. Environmental Impact
Page 64: 64 WHO, 2010. Joint FAO/WHO Expert

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